Maintaining Magnetism at High Temperature

In summary, the conversation discusses the issue of using a magnet to move 1200 degree steel, which causes the magnet to lose its magnetism at 800 degrees and potentially injure people due to falling pieces. Various solutions are proposed, such as using an electromagnet with a lot of current, using an air-core electromagnet, or using a cobalt electromagnet. The idea of insulating the contact between the magnet and the iron is also suggested, as well as using cold air blowers or a cooling station to cool the magnet during operation. Finally, it is recommended to instrument the magnet and possibly make changes to working practices to ensure safety.
  • #1
Mastone
The only way for me to move 1200 degree steel is with a magnet. The magnet loses its magnetism at 800 degrees, though, causing some pieces to fall and potentially injure people. Is there a way to electrically boost the magnetism of an existing magnet, apply an additional field to the magnet without weakening the existing field, or some other way to maintain the pull of a magnet at elevated temperatures?
 
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  • #2
If you must use a magnet, then you should consider an electromagnet with a lot of current running in it. However, are you sure that the steel you are proposing to lift can be attracted by a magnet at 1200 degrees? Have you tested it? If it turns paramagnetic below 1200 degrees, you won't be able to do it.
 
  • #3
Mastone said:
The only way for me to move 1200 degree steel is with a magnet. The magnet loses its magnetism at 800 degrees, though, causing some pieces to fall and potentially injure people. Is there a way to electrically boost the magnetism of an existing magnet, apply an additional field to the magnet without weakening the existing field, or some other way to maintain the pull of a magnet at elevated temperatures?
Welcome to the PF :smile:

Make your electromagnet out of cobalt? http://www.knowledgedoor.com/2/elements_handbook/curie_point.html (sounds expensive)

Just use an air-core electromagnet? Besides, if the iron is above its Curie temperature, how are you attracting it with a magnet?

EDIT -- beaten out by kuruman agaihn! :smile:
 
  • #4
The "steel" I referenced is an alloy and can be attracted by magnets at and above the temperature I am focused on without issue. The problem is coming from the magnet side. The magnet in use is a strong, industrial electromagnet, but, after several hours of use, begins to lose some of its magnetism due to the heat radiating from the beams. I don't think that the issue can be solved simply by "buying a better/different magnet". I think the existing magnet will have to be modified in some way to increase its magnetic properties or its resistances to heat.
 
  • #5
Mastone said:
The "steel" I referenced is an alloy and can be attracted by magnets at and above the temperature I am focused on without issue.
So it sounds like you can just make an electromagnet using that same material?
 
  • #6
If it's an industrial electromagnet it's probably wire wrapped around an iron core. The core concentrates the magnetic field lines and makes the magnet stronger. As the core heats up due to contact with the 1200 degree iron that it's lifting, it becomes less able to concentrate the field lines which makes the magnetic force weaker. Having said all that, then a possible modification would be one that keeps the magnet core cool (powerful fan?) or periodically cools the magnet while in operation.
 
  • #7
I hadn't thought of that kuruman, but that might work. My thinking was going along the lines of insulating the contact between the surface of the magnet and the iron, itself, to prevent the core from ever reaching the failure temperature. I thought about maybe introducing a vacuum at the contact point or a highly heat resistant coating, but both might not survive industrial use.

Berkeman. Thanks for that?
 
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  • #8
Use an arrangement of fixed cold air blowers which the magnet passes through each traverse .

or

Park the magnet in/on a cooling station when not being used for lifting . Plain big slab of steel with water circulation would do it .
 
Last edited:
  • #9
Fixed blowers wouldn't work because the magnet is not stationary inside the facility and a cooling station wouldn't work because the magnet doesn't have down time during the shift. The cooling would have to be attached to the unit and move with it, but I think you've given me enough ideas to move forward. Thanks a lot!
 
  • #10
If you get something to work, please keep us posted. I am curious to hear how this turns out.
 
  • #11
Can you water cool the magnet? Ideally, the coils are already water cooled, so can you increase the flow rate?
 
  • #12
Mastone said:
The only way for me to move 1200 degree steel is with a magnet. The magnet loses its magnetism at 800 degrees, though, causing some pieces to fall and potentially injure people. Is there a way to electrically boost the magnetism of an existing magnet, apply an additional field to the magnet without weakening the existing field, or some other way to maintain the pull of a magnet at elevated temperatures?
How long into the shift does it fail? Could you have several magnets used in rotation?
 
  • #13
PS if a failure of the magnet cause a hazard to humans what happens if there is a power cut? Sounds like change to working practice is also required.
 
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  • #14
Can you retro-fit the iron core with heat-pipes ? 'Passive' devices, they can shift a lot of heat for free, especially if the magnet can be parked at a 'blower' station...

I suppose the first step is to instrument the electro-magnet, mapping the heat distribution to supplement operator's 'feel'...
 

1. What is the temperature range for maintaining magnetism?

The temperature range for maintaining magnetism varies depending on the type of magnet and its composition. Generally, most magnets can maintain their magnetism up to 80-100 degrees Celsius.

2. What happens to magnets at high temperatures?

At high temperatures, the thermal energy causes the magnetic domains within a magnet to become disordered, leading to a loss of magnetism. This is known as the Curie temperature and varies for different types of magnets.

3. How can magnetism be maintained at high temperatures?

One way to maintain magnetism at high temperatures is by using materials with high Curie temperatures, such as rare earth magnets. Another method is by adding stabilizing elements, such as cobalt or nickel, to the magnet's composition.

4. What are the practical applications of maintaining magnetism at high temperatures?

Maintaining magnetism at high temperatures is crucial for various industrial and scientific applications. For example, it is essential in motors and generators that operate at high temperatures, as well as in medical equipment and aerospace technology.

5. Are there any limitations to maintaining magnetism at high temperatures?

Yes, there are limitations to maintaining magnetism at high temperatures. As the temperature increases, the magnet's strength decreases, and it may eventually lose all its magnetism. Additionally, the materials used to maintain magnetism at high temperatures can be expensive and may not be suitable for all applications.

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